Barremian-Aptian-Albian carbon isotope segments
as chronostratigraphic signals: Numerical age
calibration and durations
R. W. Scott
Precision Stratigraphy Associates and The University of Tulsa,
149 West Ridge Road, Cleveland Oklahoma 74020, USA
email: [email protected]
ABSTRACT: Chemostratigraphic signals are becoming common tools in chronostratigraphic correlations. Specifically total organic and
carbonate carbon percentages (TOCorg/carb) and carbon isotope curves are diagnostic in Cretaceous Aptian-Albian-Cenomanian strata.
Cretaceous carbon isotope signals define oceanic anoxic events (OAEs) and have been subdivided into successive segments. These segments are used as correlation markers because they represent oceanographic and depositional conditions, and hence, incur time significance. Although the segments have been integrated with biovents in key sections, numerical ages of the segments have yet to be calibrated.
Because direct correlation of these segments of carbon isotope curves with interbedded radiometrically dated beds is not possible currently, other methods must be applied to interpolate numerical ages. Graphic plots of five sections successfully integrate carbon isotope
segments with established numerically dated chronostratigraphic markers. Carbon isotope segments were first defined in European Tethys
Cismon and Rotter Sattel Barremian-Albian sections. The Aptian segments were subsequently identified in the Mexican Santa Rosa Canyon section where the lower Albian segments were defined. Each section has well documented microfossils and magnetochrons that relate
the segments to biozones. These bioevents and chronozones enable the carbon segments to be integrated with a comprehensive Cretaceous
time scale, the CRECSDB42. Ages assigned to the segments enable them to be used in sections where local fossil zones are recorded such
as in the Chihuahua basin in northern Mexico. The age calibration of carbon isotope segments measures the durations of the oceanic isotopic excursions. The durations fluctuate up to and after OAE 1a at irregular frequencies different from climatic cycles. Changing durations
of carbon isotope segments may be clues to changes in processes or the effects of the process that altered the ocean carbon reservoir in addition to climatic changes.
Key words: Carbon isotope chemostratigraphy, Barremian, Aptian, Albian, Tethys
INTRODUCTION
Chemostratigraphic signals have become common, widespread
tools in chronostratigraphic correlations (Jarvis et al. 2006;
Jenkyns 2010; Di Lucia et al. 2012) because they are “linked directly to the biosphere and the global carbon cycle” (Saltzman
and Thomas 2014). If chemostratigraphy is integrated with
chronostratigraphic data from biostratigraphy and magnetostratigraphy, it becomes a reliable tool for correlation (Weissert
et al. 2008). The two most widely used chemostratigraphic signals are those of total organic carbon (TOC) and the d13C ppm
of bulk carbonate. Total organic carbon percentages in organic-rich sedimentary rocks (TOCorg/carb) are named lithostratigraphic units, such as “Livello Selli” in the Italian
Apennines (Menegatti et al. 1998). One hypothesis posits that
such deposits represent ‘biocalcification crises’, which were
“times of reduced calcification rates…causing widespread carbonate platform collapse…” (Weissert and Erba 2004). These
events affected the global carbon isotope budget. As a result,
the d13C signal of both pelagic and shelf limestone fluctuated.
An alternative hypothesis is that orbitally-induced climate
changes controlled sea level and terrestrial erosion so that alternating organic-rich deposits were dominated by either oceanic
or terrestrial organic matter (Erbacher et al. 1996).
During much of the Albian, carbon isotope fluctuations corresponded to the ~400 kyr orbital cycle recorded in pelagic
mudstones of the Marne a Fucoidi Formation, Central Apennines,
Italy (Giorgioni et al. 2012). These researchers proposed that carbon isotope fluctuations were related to periods of stronger and
weaker contrasting monsoon seasons. Lower d13C measurements
correspond to greater seasonal contrasts and higher isotope peaks
relate to eccentricity minima with weaker climate contrast. Cretaceous ocean circulation may have been driven by deep eddies that
influenced seasonal monsoons (Hay 2007). Stronger ocean eddies
and stronger monsoon seasons may have reduced the rate of organic carbon burial thus decreasing oceanic carbon isotope composition. Stronger monsoons would increase weathering and
erosion resulting increased influx of light carbon from continental plants. Weaker eddies and monsoonal seasons would increase
burial rates of organic carbon and decrease erosion resulting in
increased in d13C. For example black shale with high terrestrial
matter correspond with eccentricity maxima and pelagic marine
red beds, which reflect oxygenated bottom waters (Hu et al.
2012) correspond with eccentricity minima (Giorgioni et al.
2012, fig. 4).
The isotopic variations of total bulk inorganic carbon in carbonate strata have been divided into successive carbon isotope segments (C). Carbon and oxygen isotope curves are now
documented in many pelagic and shelf Cretaceous sections
(Jenkyns et al. 1994; Leckie et al. 2002; Weissert and Erba 2004;
Herrle et al. 2004; Wissler et al. 2003; Stein et al. 2011; Di Lucia
Stratigraphy, vol. 13, no. 1, text-figures 1–8, table 1, appendix 1, pages 21–47, 2016
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R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
et al. 2012; Giorgioni et al. 2012; Saltzman and Thomas et al.
2012; Gamacorta et al. 2015). These segments are used as correlation markers because they represent oceanographic and
depositional conditions, and hence, incur time significance
(Menegatti et al. 1998; Wissler et al. 2002; Wissler et al. 2003;
Föllmi et al. 2006; Burla et al. 2008). The most dramatic isotope peaks were initially identified in organic-rich black shale
deposits and define oceanic anoxic events (OAEs). The proportions of 13C and 12C in marine waters vary by photosynthesis, deposition of organic matter, weathering rates, and
submarine volcanism (Kump and Arthur 1999; Saltzman and
Thomas 2014). Marine algae concentrate 12C in organic matter
thereby increasing d13C in ocean water and in carbonate minerals. The resulting sediments are black shale depleted in 13C and
limestone depleted in 12C. The carbon isotope amount is affected by a complex set of interacting factors (Leckie et al.
2002; Saltzman and Thomas 2014) and during the Cretaceous
fluctuated greatly (Veizer et al. 1999) even as the amount of
modeled atmosphere CO2 declined (Berner and Kothavala
1999).
Several challenges emerge with the use of geochemical signals
as chronostratigraphic markers. First is that the shape and precision of the curves are related to sample density. The sample
spacing varies depending on the rate of sediment accumulation;
closer spacing is required in thinner intervals deposited at
slower rates. A second issue is unraveling the effects of
diagenesis from the original deposition signal. Verifying that an
original depositional signal is recorded is based on multiple
analyses, which have been clearly outlined by various authors
(Menegatti et al. 1998; Bralower et al. 1999; Wendler et al.
2009; Jenkyns 2010; Wendler 2013). A third challenge is to define consistently and objectively the segment boundaries in the
curve. Many geochemical curves are asymmetric and the curve
trends are irregular and of different magnitudes; some curve
shifts are abrupt and some are gradual. Placement of a boundary
may be at the acme or the nadir, or at the beginning or ending or
mid-point of the inflection, or part way along a gradually declining slope. A fourth challenge in using chemostratigraphic
curves as chronostratigraphic markers is the lack of uniqueness
of curve segments, so the segments must be integrated with precise biostratigraphic or magnetostratigraphic events. However
carbon and oxygen isotope curves of strata younger than about
5 Ma seem to have distinctive characteristics that represent the
400 kyr eccentricity orbital cycles (Berggren and Burckle 1997;
Wang et al. 2010).
These issues have been well addressed by studies of numerous
Cretaceous Tethyan hemipelagic sections (text-fig. 1), in which
the carbon isotope signal of bulk carbonate and of organic matter have been subdivided into discrete segments. Eight carbon
isotope segments were initially defined in the Roter Sattel section, Switzerland, and the Cismon core, Italy (Menegatti et al.
1998). Subsequently segments C9 to C15 were defined in the
upper Aptian-lower Albian pelagic section in Santa Rosa Canyon, Mexico (Bralower et al. 1999) (text-fig. 1). These segments are identified here in the high-resolution isotope curve of
the core on Resolution Guyot (Jenkyns 1995; Jenkyns and Wilson 1999). Barremian carbon isotope segments B1-8 were first
defined in the Cismon core and correlated with sections in the
Swiss Alps, which were based on bulk rock samples of carbonate ramp limestone and marl (Wissler et al. 2002).
22
Subsequently carbon isotope segments were defined in a composite set of carbonate sections in southeastern France (Huck et
al. 2013; 2014) and offshore Morocco in DSDP 545, which
were given a different nomenclature (Herrle et al. 2004). The
segments of Herrle et al. (2004) have been identified in Sonora
(Madhavaraju et al. 2013). In the Pyrenees of Spain Barremian-Aptian segments are also described (Sanchez-Hernandez, Y. and Maurrasse 2014a, 2014b). Further examination of
carbon isotope increment C7 resulted in dividing it into four
subunits (Nuñez-Useche et al. 2014).
Upon shallow-water Tethyan carbonate platforms in the Mediterranean area, Barremian-Albian metric-scale shoaling-up cycles are defined by exposure contacts (d’Argenio et al. 2004;
Wissler et al. 2004). Cyclostratigraphic analysis of lithostratigraphic cycles relates these to ~400 kyr-long eccentricity
frequency. The carbon isotope signal in these platform sections
is correlative with pelagic curves where constrained by
magnetostratigraphic and biostratigraphic data.
The first purpose of this note is to calibrate numerical ages of
Barremian-Albian carbon isotope segments defined by Menegatti et al. (1998), Bralower et al. (1999) and Wissler et al.
(2002) and to integrate these segments with other biostratigraphic events. The integration of carbon isotope segments with
biostratigraphic events in CRETCSDB4 (Scott 2014) has the
potential to correlate stage boundaries of reference sections
with signals in other sections. Second, precise numerical ages of
Barremian-Albian carbon isotope segments will provide rates of
change of processes that altered the oceanic carbon cycle.
METHOD OF INTEGRATION
The Cretaceous Chronostratigraphic Database CRETCSDB4
was constructed by graphic correlation, which is a transparent,
testable method that integrates stratigraphic data. Graphic correlation is a quantitative but non-statistical technique that enables stratigraphic correlation experiments between two
sections by comparing the ranges of event records in both sections (Edwards 1989; Carney and Pierce 1995). A graph of any
pair of sections is an X/Y plot of the FOs (first appearances) and
LOs (last appearances) of taxa found in both sections. To propose coeval relationships between sections, the interpreter
places a line of correlation (LOC) through the tops and bases
that are at their maximum range in both sections. This LOC is
the most constrained hypothesis of synchroneity between the
two sections and adjusts the ranges of the fewest bioevents. The
LOC also accounts for hiatuses or faults at stratal discontinuities
indicated by the lithostratigraphic record. The position of the
LOC is defined by the equation for a regression line. Carney
and Pierce (1995) explained the process and provided examples
of the graphic technique.
A species range database such as CRETCSDB4 is compiled by
iteratively graphing successive measured sections or cores and
integrating ranges of all sections. Because the software
GraphCor, a DOS-based system, has a limited storage capacity,
sets of sections are grouped into subprojects of up to fifty sections of composited ranges that are then saved separate databases. The progressive subprojects that compose CRETCSDB4
are MIDK3, MIDK4, MIDK 41, MIDK45, CRET1, CRET2,
and CRETFIX (Scott 2014). If a section in a preceding
subproject is plotted to the next project, the plot will be a
straight line because the data of the section is already in the
composited dataset. The accuracy of these ranges depends on
Stratigraphy, vol. 13, no. 1, 2016
TEXT-FIGURE 1
Cretaceous geologic time scale calibrated by Gradstein et al. (2012) and Scott (2014) with composited carbon isotope curve of Weissert and Erba (2004),
Jarvis et al. (2006) as presented by Steuber et al. (2015). Anoxic segments from Jenkyns (2010). Ma = megaannums. OAE = oceanic anoxic event.
23
R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
TEXT-FIGURE 2
Cretaceous paleogeography about 90 Ma as Mollweide projection showing relative locations of the Roter Sattel section (1), the Cismon core (2) and the
Santa Rosa Canyon section (3) (red pentagon symbols). From Dr. Ron Blakey website: <http://jan.ucc.nau.edu/~rcb7/>.
the number of sections, preservation and correct identification
of the species. Event sequences and ages compiled by graphic
correlation can be tested and fully evaluated because the
sources of the data are available. In addition, the order of segments in different basins can be compared.
CRETCSDB4 is a compilation of more than 3500 taxa and
marker beds in more than 295 published sections calibrated to a
mega-annum scale (Scott 2014). The database spans the Jurassic/Cretaceous and the Cretaceous/Paleogene boundaries. Construction of CRETCSDB4 began by plotting bioevents in the
Kalaat Senan, Tunisia, Cenomanian-Turonian section to the
1989 time scale (Harland et al. 1990), which was subsequently
adjusted to the 2004 time scale (Gradstein et al. 2004, 2012).
The sedimentology, sequence stratigraphy, and biostratigraphy
of the Kalaat Senan section were precisely documented and
stage boundaries defined biostratigraphically (Robaszynski et
al. 1993). Non-biotic data such as chemostratigraphic curves
and sequence boundaries were incorporated into the database
by including these segments with associated fossils in key reference sections (Edwards 1989). Groups of sections were combined into the database in successive subprojects, including the
MIDK3, MIDK4, MIDK41, MIDK45, CRET1, and CRET2 databases that combine to compose CRETCSDB4. Additional
24
sections with radiometrically dated beds were graphed to constrain the accuracy of the numerical scale. Ranges of first and
last occurrences are calibrated to mega-annums of Cretaceous
stages defined by GSSPs or reference sections. This database
serves as a look-up table for interpolation and age calibration of
other stratigraphic sections. The age ranges of some taxa and
marker beds are preliminary and may be extended as new sections are added to the database.
CARBON ISOTOPE SECTION DATA
Barremian-Aptian carbon isotope segments were first identified
in three Aptian basinal hemipelagic sections; two are in a rifted
basin on the European side of the Tethys Ocean, at Cismon, Italy
and Roter Sattel, Switzerland, and one section is in the Gulf of
Mexico at Santa Rosa Canyon, Mexico (text-fig. 2; Appendix 1).
Planktic foraminifera and nannoplankton are well preserved in
each section and provide biostratigraphic control. The Cismon
120m-thick cored section is in the Venetian Alps of Northern Italy (Erba and Larson 1998; Erba et al. 1999; Wissler et al. 2002;
Channell et al. 1979; 2000); a nearby outcrop section confirms
the biostratigraphy (Bralower 1987). Magnetochrons M3r to M0r
are identified in the Cismon cored section. The Roter Sattel section is in the Swiss Préalpes Médianes Plastiques and a
Stratigraphy, vol. 13, no. 1, 2016
TEXT-FIGURE 3
Graphic plots of Cismon core (A) and Roter Sattel section (B) compared to the Cretaceous composited database. Square symbols = first occurrence or base
of event; + = last occurrence or top of event; bases of geochemical segments are red squares; B1-6 and C1-8 are the bases of geochemical segments. A.
Cismon core with line of correlation constrained by magnetochrons and Aptian bioevents. A slight disconformity or condensed interval is present at -25m
at the base of the Livello Selli black shale. This plot first projects geochemical segments B-1-8 and C-1-8 into the numerical database; isotope curve from
Erba et al. (1999) and Wissler et al. (2002, 2003). B. Roter Sattel outcrop section with line of correlation of Aptian interval constrained by OAE 1a and Selli
bed. Base of C8 is above correlation line and LO of Leupoldina cabri by 2.9m, which is 2.18m higher than in Cismon core, which suggests that the boundary may be placed too high at Roter Sattel. At base of section C2 segment may define alternative LOC.
25
R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
TEXT-FIGURE 4
Graphic plot of Santa Rosa Canyon section compared to the Cretaceous composited database (Symbols as in text-figure 3). Santa Rosa Canyon Aptian
section line of correlation constrained by magnetochron M0R, OAE 1a and carbon segments set at Cismon and Roter Sattel. Numerical ages of Carbon
isotope segments 9 through 15 calibrated to numerical ages by projecting metric position (red arrow) into upper Aptian-Albian interval by correlation
line constrained by Niveau Jacob black shale, OAE 1b and bioevents.
bed-by-bed description documents the foraminifers and carbonate carbon isotope (Strasser et al. 2001). The Aptian-Albian interval is about 38m thick. The Santa Rosa Canyon outcrop
section, Nuevo Leon, Mexico, is in the Sierra Madre Oriental and
is 220m thick spanning basal Aptian to lower Albian.
At the Cismon cored section, bulk carbonate and organic carbon
isotopes were measured on samples at a spacing of six to seven
per meter (text-fig. 3A). These were divided into eight Aptian
and five Barremian segments based on mean d13Ccarb and d13Corg
values (Menegatti et al. 1998; Erba et al. 1999; Wissler et al.
2002). Subsequently Wissler et al. (2003) further divided the
upper Barremian and basal Aptian at Cismon into segments B6
to B8 and A1 to A4; segments B8 through A4 overlap segments
C2 to C4 of Menegatti et al. (1998). The maximum differences
in the curve are up to 3.8‰; some changes are abrupt and some
gradational and boundaries are close to the inflections points of
the shifts (Menegatti et al. 1998, figs. 2, 3; Erba et al. 1999, fig.
7). The Cismon section was plotted to the MIDK4 project,
which is an early substage of CRECSDB4 (text-fig. 3A). The
line of correlation is defined by magnetochrons, nannofossils
and planktic foraminifera. The numerical ages of the bases of
B1 to B8 and C to C8 were first projected into the database by
this LOC.
26
Carbonate carbon isotope data in the Rotter Sattel section
(text-fig. 3B) were derived from a spacing of six samples per meter (Menegatti et al. 1998, fig. 2). Some boundaries are very
abrupt and others are at slopes between peaks. Planktic
foraminifer biostratigraphy constrained the positions of the LOC.
The boundaries of the d13Ccarb and d13Corg curve segments plot on
the LOC consistently as defined in the Cismon section. The base
of C1 was not included because the section was not logged below
the event base. C8 is left of the LOC and is higher in the section
compared to its position and age in Cismon section; this suggests
that its base was picked at different points on the curves in the
two sections. The C7— C8 boundary in the Roter Sattel section is
more gradational than in the Cismon section.
In the Roter Sattel section the Aptian-Albian unconformity at
32.25m is slightly above the base of C8 and no higher segments
were noted by Menegatti et al. (1998, fig. 2). The graphic plot to
the subproject MIDK41 of CRETCSDB4 suggests either a brief
hiatus at the base of OAE 1a between C2 and C3 or a condensed
interval (text-fig. 3B). An Aptian/Albian unconformity in both
the Roter Sattel and Cismon sections limits the sequence of geochemical segments.
In the Santa Rosa Canyon section, Nuevo Leon, Mexico
(text-fig. 4), samples were collected one meter apart and the or-
Stratigraphy, vol. 13, no. 1, 2016
TEXT-FIGURE 5
Event ranges in Santa Rosa Canyon section compared to event ranges in Roter Sattel section showing that these segments are the same age in both sections.
Line of correlation in Aptian interval is constrained by carbon isotope segments. Symbols as in text-figure 3. Unconformities (solid lines) are similar ages
and conformable time lines (dashed lines) in Roter Sattel correlate with unconformities in Santa Rosa section.
ganic carbon of carbonate was measured. The total organic carbon content of the samples was generally less than 0.5%. The
d13Corg values extend across unconformities into the Upper
Albian Eiffellithus turriseiffellii and Biticinella breggiensis
zones; bulk carbonate was not analyzed (Bralower et al. 1999,
fig. 7). In addition to identifying C1 through C8, younger carbon segments C9 through C15 were defined. The boundary positions of the segments are on the inflection slopes between
peaks or on the peaks themselves. Some segments correspond
to peaks of total organic carbon and of CaCO3%. Because curve
segments are not unique, biostratigraphy was used to identify
the older carbon segments. Nannofossil biostratigraphy (Bralower et al. 1999, fig. 3) was supplemented by planktic
foraminifera, calpionellids and nannoconids (Longoria 1974,
1998; Ice and McNulty 1980; Sliter 1992). The chronostratigraphic interpretation of the section is constrained by
magnetochron M0R at the base and the normal succession of
nannofossil and planktic foraminifer zones up to basal Upper
Albian (text-fig. 4).
The graphic plot of the Santa Rosa data to the Cretaceous
Chronostratigraphic database (text-fig. 4) suggests discontinuities in the record of deposition based on offsets in the lines of
correlation. These unconformities or condensed intervals had not
been identified in Santa Rosa section previously. In the upper part
of the La Peña Formation an unconformity is postulated at about
192m in the Globigerinelloides algerianus Zone above the base
of segment C8, which is dated at 122.12 Ma. This level is the base
of a 2‰ negative d13Corg shift and a 2.5% TOC peak, which is inferred to be the Niveau Jacob black shale bed projected at 115.13
Ma. This organic-rich bed is overlain by the Tamaulipas Limestone with OAE 1b in its basal part dated at 112.09 Ma. A second
unconformity or condensed interval is proposed in the uppermost
part of the La Peña at 210m between the LO of G. algerianus and
the FO of Colomiella recta. Segments C9 and C10 are within this
interval, which determines the projected age of these carbon isotope shifts. A higher unconformity at about 300m is between the
Tamulipas and Cuesta Del Cura formations at a thin shale bed that
overlies base of segment C15 and underlies the first occurrences
27
R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
TEXT-FIGURE 6
Graphic plot of Resolution Guyot carbon isotope data relative to events in the advanced CRETFIX Database with the FOs positions of four planktic
foraminifera projected by their relative positions with isotope events in the Cismon section by Jenkyns (1995). The base of the Aptian defined by the base
of magnetochron M0R is at the base of carbon segment B8/C2 at -1100/-1080 mbsf. The base of the Albian as defined here by the FO of Leymeriella
tardefurcata falls between the FOs of C10 and C11 -400 to -330 mbsf. Planktic foraminifers were not identified in the shallow shelf facies.
of Upper Albian Eiffelithus turriseiffelii and Biticinella breggiensis. The hiatus at this unconformity was correlated with a
regional unconformity on the shelf interior of North Texas between the Fredericksburg and Washita groups Albian sequence
boundary Al Wa 1 (Scott et al. 1988, fig. 4; Scott et al. 2003).
The carbon segments in the Aptian portion of the Santa Rosa
section correlate well with those in the Roter Sattel section
(text-fig. 5). In both sections an unconformity is plotted above
the base of C8, although deposition persisted longer during
event C8 at Roter Sattel than at Santa Rosa. This plot supports
the correlation of Aptian carbon curve segments at Santa Rosa
with those at Roter Sattel.
The Albian carbon isotope data is quite complex and not readily
subdivided into unique segments. A rich dataset of deep benthic
foraminifers from five different basins has a 4‰ spread of d13C
without distinct segments (Friedrich et al. 2014, fig. 2). Furthermore, in the Albian Marne a Fucoid Formation at Mont Petrano,
Italy, the amplitude of the cycles diminishes from about 0.75
28
ppm to 0.4 ppm (Giorgioni et al. 2014). These datasets suggest
that oceanic processes shifted during the Albian (Giorgioni et
al. 2014; Friedrich et al. 2014).
In order to test the correlation potential of Albian carbon isotope
segments C9 to C14 the high resolution carbon isotope dataset
of the Resolution Guyot core (Jenkyns 1995; Jenkyns and Wilson 1999) was graphed with the data at Santa Rosa Canyon in
the CRETFIX database (text-fig. 6). This Mid-Pacific section
spans a nearly 1600m-thick Barremian-Albian interval. This
subtidal-intertidal carbonate section was deposited upon a basaltic edifice dated at 127.6±2.1 Ma (Jenkyns 1995) and re-calibrated to 123.63±0.9 Ma (Pringle in Larson and Erba 1999) so
the oldest carbonate deposition was early Barremian, which began about 130 Ma (Ogg et al. 2012; Scott 2014). Supplementary
chronostratigraphic control is limited in this section. The Selli
marker bed was identified as a sixty meter thick interval of cyclic packstone-wackestone and algal laminite with clay and organic-rich laminae from 860m to 800m and a strongly negative
carbon isotope peak (Jenkyns 1995) identified here as C3. The
Stratigraphy, vol. 13, no. 1, 2016
TEXT-FIGURE 7
Chemostratigraphic correlation of five key Tethyan carbonate sections that span the Barremian to Albian stages and that define the chronostratigraphic order of Carbon Isotope segments B1 to C15. Data for the Angles section from Wissler et al. (2002); for the Cismon section from Erba et al. (1999, fig. 7) and
Menegatti et al. (1998, figs. 2, 3); for the Roter Sattel section from (Strasser et al. 2001; Menegatti et al. (1998, figs. 2, 3); and for the Santa Rosa section
from Bralower et al. (1999, figs. 3, 7). Ammonite zonation of the Angles section is by Wissler et al. (2009): Av=Ancycloceras vandenheckei;
Dt=Deshayesites tuarkyricus; Dw=Deshayesites weissi; Gs=Gerhardtia sartousiana; Hc=Holcodiscus caillaudianus; Hf=Hemihoplites feraudianus;
Ig=Imerites giraudi; Kn=Kotetishvilia nicklesi; Ms=Martelites sarasini; Sh= Spitidiscus hugii [=Th=Taveraidiscus hugii]; Sn=Subpuchellia nicklesi;
Tv=Toxancyloceras vandenheckii.
first occurrences of key Aptian planktic foraminifera were projected into the section by relating them to carbon isotope peaks
in sections where the fossils are present (Larson and Erba
1999). Direct paleontological evidence of the Aptian age of the
Resolution carbonates is the presence of the rudist bivalve,
Conchemipora skeltoni Chartrousse and Masse (1998) at 917.0
mbsf. In the absence of other fossil data in the core, the
Albian/Aptian boundary was approximated by 87Sr/86Sr curve
(Jenkyns and Wilson 1999, fig. 5).
Identification of the carbon isotope segments defined in the
Mediterranean and Mexican sections (text-fig. 6) is derived by
comparing the curve parts below and above the strong negative
peak C3. The first trial to identify lower Aptian-Barremian segments below C3 was to assume that basal Barremian B1 was the
basal segment and segments were partitioned up to C3. However, the interval below C3 is too thin to accommodate segments B6-8. The second trial was to identify segments
downward from C3 ending with B4 at the base. This resulted in
a graphic interpretation (text-fig. 6) that projects the
Barremian-Aptian contact near the base of C2 at about 930m.
Carbon isotope segments above C3 match the placement of the
segments in the Santa Rosa section up to C14, which on Resolution Guyot is truncated by a drowning unconformity marked by
a manganese hardground. Within the interval 450 to 300m calcrete contacts are numerous and the carbon isotopes segments
are thin, which is consistent with numerous brief hiatuses of
subaerial exposure.
Wissler et al. (2002) first defined Barremian segments in the
Cismon core data of Erba et al. (1999) and in the Angles, France
section. The B1 to B5 and A1 to A4 segments were projected into
the CRETCSDB4 by graphing these sections (text-fig. 3B). Subsequently Barremian-lower Aptian carbon isotope data were documented in two Swiss outcrop sections, Alvier and Churfirsten.
Carbon isotope data were measured on bulk samples of limestone
and marl (Wissler et al. 2003). The Barremian-lower Aptian interval at Alvier is about 440m thick and the Churfirsten section is
200m thick; at both sections sample spacing was about 2m.
These two Swiss carbonate sections are bounded by a basal
transgressive disconformity with Hauterivian-lower Barremian
ammonites and by Upper Aptian ammonites above the topmost
disconformity. The inclusion of these two sections confirmed the
age interpolation of these isotope curves and their plots are not illustrated.
INTEGRATION WITH BIOEVENTS AND
MAGNETOCHRONS
Foraminiferal zones are documented in two of the three key
Aptian sections based on the first occurrance datum (FO) (Table
1). Segments C1 through C6 are within the Globigerinelloides
29
R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
TEXT-FIGURE 8
Plot of carbon isotope segment durations versus time in mega-annums based on Table 1. Segments below unconformities and Wissler segments B8, A1,
A2, and A3 that overlap C1, C2 segments are not included. Barremian durations fluctuate decreasing into OAE 1a, which is followed by a long period C7.
Complete segment C8 is not shown because it is cut by a regional unconformity. Upper Aptian carbon isotope segment fluctuate decreasing into OAE 1b,
which is followed by long segments C11 and C14. Leenhardt and Urbino black shale beds were deposited during isotope segment C11 and C12.
blowi Zone at the base of the Cismon and Rotter Sattel sections.
The base of C7 is just below the base of the Leupoldia cabri
Zone and ranges to the top of this zone. Segment C8 extends
through the overlying Globigerinelloides ferreolensis and
Globigerinelloides algerianus zones at Roter Sattel and is overlain by the Aptian-Albian unconformity in both sections
(Menegatti et al. 1998; Strasser et al. 2001). At Santa Rosa thin
C9 is in the uppermost part of the Globigerinelloides algerianus
Zone and C10 begins in the Hedberella planispira-Ticinella
bejaouaensis Zone and C11-12 span to the top of this zone. C13
and C14 span the Ticinella primula Zone. A disconformity separates C14 from C15, which spans part of the Biticinella
breggiensis Zone.
Nannofossil zones are documented in the Cismon core and the
Santa Rosa outcrop. Segment C1 begins in the lower part of the
Chiastozygus litterarius Zone NC6 identified by the first occurrence (FO) of Rucinolithus irregularis (Bralower et al. 1999)
(Table 1). Segments C4 through C10 range through the
Ragodiscus angustus Zone NC7 identified at Santa Rosa Canyon by the FO of Eprolithus floralis. Segments C11 through
C14 are within the Prediscosphaera columnata Zone NC8 and
the Axopodorhabdus albianus Zone NC9, which are undifferentiated at Santa Rosa Canyon.
In the Cismon cored section magnetochrons M0R to M9R (Erba
et al. 1999) are integrated with nannofossils and carbon isotope
30
segments (Menegatti et al. 1998). Segment C1 corresponds with
Chron CM1R and C2 overlaps with Chron CM0R (text-fig. 2).
However in the Santa Rosa Canyon section C1 extends across
CM0R and C2 is younger beginning above CM0R. A comparison of the carbon isotope curves by Menegatti et al. (1998, fig.
3) with curves by Erba et al. (1999, fig. 7) and by Bralower et al.
(1999, fig. 7) indicate that the base of C2 is defined at different
places on the curves.
The base of carbon segment C3 is slightly younger than the onset of the nannoconid crisis and the base of C5 is virtually the
same age as the beginning of OAE 1a in these sections (Table
1). In the younger part of the late Aptian-early Albian, carbon
segments C9 to C12 in Santa Rosa section correlate in part with
black shale beds defined in Italian sections although the beginning ages are not coincident.
No ammonites were recorded at the three sections but ammonite
first occurrences can be correlated with the carbon isotope segments by the integration of ammonites from other sections that
also yield nannofossils and planktic foraminifers (Table 1). The
FO of the basal Aptian Deshayesites oglanlensis is in C2. The
FO of Epicheloniceras martini in the Upper Aptian Substage is
within C7. The lowermost Albian Leymeriella tardefurcata and
Leymeriella schrammeni schrammeni dated at 112.46 Ma correlate within C10. One well preserved rudist specimen in the Res-
Stratigraphy, vol. 13, no. 1, 2016
TABLE 1
Numerical ages of carbon isotope events compared to bioevent ages. The age of the base of a segment defines the age of the top of the preceding segment so
the age of the top is redundant. Most last occurrences of taxa and magnetochrons do not constrain the line of correlation and most zones are defined by the
FO, so only the ages of the FO of carbon segments are compared to FO of bioevents. Ages from CRETCSDB4 (Scott 2014; precisionstratigraphy.com).
olution core is the Aptian Conchemipora skeltoni at 917.0 mbsf
(Chartrousse and Masse 1998) in the lower part of segment C2.
heckii in the Angles and Cismon sections falls in the upper part of
isotope event B2.
Because the carbon isotope segments are defined in hemipelagic basin sections, correlation of carbon segments with
shelf sections where short-term hiatuses are numerous is uncertain (Quesne and Ferry 1995; Di Lucia et al. 2012). However,
where shelf cycles are integrated with magnetochrons and
OAEs, and carbon isotope curves are similar to nearby basin
curves, there sea-level segments can be correlated with basin
successions (d’Argenio et al. 2004; Wissler et al. 2004).
The Barremian-Aptian boundary can be consistently identified in
all five sections. In the absence of a GSSP, this stage boundary is
positioned approximately at the base of Magnetochron M0R and
the first occurrence of the ammonite, Deshayesites oglanlensis or
the alternative species at Angles, Deshayesites tuarkyricus. In the
Cismon section the boundary is within carbon event C2
(Menegatti et al. 1998) and at the contact of B8 and A1 (Wissler
et al. 2002, 2003). At Roter Sattel, Switzerland Menegatti et al.
(1998) placed the base Aptian at the contact of C1 and C2. However, C1 was defined by four points at the base of the section so
that no clear definition of the C1-C2 boundary is recorded. Also
in the Santa Rosa, Mexico, section the basal data points were
identified as C1 (Bralower et al. 1999) but could also be part of
C2.
GLOBAL CORRELATION POTENTIAL
To be used as a chronostratigraphic tool carbon isotope curve
segments must be related to independent criteria such as species
FO or LO or magnetochrons; they must be consistently identified and represent segments of widespread oceanic changes.
The carbon isotope datasets of five outcrop and cored sections
in southern Europe, North America and the Pacific Ocean are
integrated with independent chronostratigraphic markers and
their curve shapes are relatively consistent and identifiable
among the sections (text-fig. 7).
Lower Barremian strata at the Angles and Cismon sections conformably overlie Hauterivian sedimentary strata and span the
Taveraidiscus hugii and Kotestishvilia nicklesi zones (Wissler
et al. 2009). Carbon isotope event B1 spans these zones and the
boundary with B2 is within Magnetocrhon CM3R at Cismon
(Menegatti et al. 1998). The lower-upper Barremian boundary
defined by the first occurrence of Toxancycloceras vanden-
In the Lower Aptian, the sharp light carbon isotope peak C3 is the
same age as the base of the Selli bed and slightly younger than the
isotope inflection point used to define the beginning of OAE 1a.
The closely spaced isotope segments C4-C6 are within OAE 1a.
The positive peak used to define C7 approximates the end of the
anoxic event.
Until a global section and stratal point is picked for the base of the
Albian Stage, multiple criteria have been proposed: first occurrence of Microhedbergella rischi/renilaevis at 113.32 Ma,
Leymeriella schrammeni anterior at 113.51 Ma and Leymeriella
tardefurcata at 112.68 Ma (Petrizzo et al. 2012; Kennedy et al.
2014). These bioevents fall within carbon isotope event C10,
31
R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
which spans 114.55-111.74 Ma. Carbon event C10 is a relatively positive interval bounded below and above by sharp light
peaks in the Santa Rosa and Resolution Guyot sections. In the
Cismon and Roter Sattel sections the Aptian-Albian boundary
is an unconformity.
DURATIONS OF CARBON ISOTOPE SEGMENTS
The age calibration of carbon isotope segment bases measures
the durations of the oceanic isotopic excursions (table 1,
text-fig. 8). The age-duration plot shows fluctuating but gradually shorter carbon isotope segments leading to OAE 1a, which
is followed by three very brief segments C4, 5, 6. This was followed by long C7 and C8, which was truncated by submarine
unconformities in Cismon, Roter Sattel and Santa Rosa sections; the maximum duration of this hiatus was from 120 to
115.2 Ma. This hiatus was followed by short-term carbon burial
segments represented by black shale beds Jacob, Kilian,
Paquier, Leenhardt, and Urbino that clustered around OAE 1b.
Long-period segments followed through the Early and Middle
Albian Age. Changing durations of carbon isotope segments
may be clues to changes in processes or the effects of the process that altered the ocean carbon reservoir. During the
Barremian-Aptian interval, d13C spiked from 1 to 3.5‰ (Veizer
et al. 1999, fig. 10), even as atmospheric CO2 declined steeply
(Berner and Kothavala 1999, fig. 13). Associated increased marine productivity and carbon burial suggest “widespread
changes in the ocean-climate system” (Leckie et al. 2002). The
very negative carbon isotope shift C3 is found in many Lower
Aptian shelf-slope-basin sections. Aptian sea-floor spreading
rates increased significantly (Seton et al. 2009). Beginning in
Late Barremian crustal production increased by 44% from
about 18 to 26 km3/yr-1 and during early-middle Aptian production increased further 35% to 35 km3/yr-1 (Leckie et al. 2002;
Kelley 2003, fig. 7.16). Increased crustal production accounts
for emplacement of the large igneous provinces (LIP) Ontong
Java I-Mannihiki and Kerguelen I. Carbon isotope shifts in sedimentary strata may be related to one or more of three processes
(Leckie et al. 2002): 1) increased upwelling of nutrient-rich and
12
C-rich waters (Menegatti et al. 1998); 2) increased weathering
rates related to increased CO2 and warmer atmosphere
(Menegatti et al. 1998); and 3) injection of light mantle-derived
CO2 by LIP eruption followed by OAE 1a carbon burial
(Larson and Erba 1999).
The mean duration of the twenty-one Barremian-early Albian
segments is 587 kyr, which differs from the climatic cycle frequencies. However light and dark marl beds of the Selli Level
in the Cismon core record eccentricity, (400 kyr), obliquity (36
kyr) and precession (20 kyr) (Huang et al. 2010). In the Central
Apennines, Italy, carbon isotope of bulk carbonate of Albian
marl records the 400 kyr cycle (Giorgioni et al. 2012). These
authors conclude “that the cyclic pattern in the d13C curve reflects changes in the isotopic composition of the dissolved inorganic carbon in the photic zone of the Tethys during the Albian”
(Giorgioni et al. 2012). These regular lithological cycles reflect
the ocean-atmosphere climatic interaction. The irregular carbon isotope segments of the Barremian-early Albian may have
responded to other processes such as submarine volcanic eruptions or changes in sea floor spreading rates or they could be divided more finely. The durations of the carbon isotope
segments suggest that fractionation rates of light carbon from
13
C were abrupt.
32
CONCLUSIONS
Carbon isotope curve segments are integrated within the Cretaceous Chronostratigraphic Database by plots of the Roter Sattel,
Cismon and Santa Rosa Canyon sections based on shared
bioevents and magnetochrons. The bases of these carbon isotope segments acquire numerical ages by these correlations
(table 1). These ages then are compared with the ages of the FOs
of ammonites, planktic foraminifer and calcareous nannofossils
that define the standard Aptian-Albian zones. Thus these geochemical records are correlated with criteria that define the suggested stage and substage boundaries (Reboulet et al. 2011),
although no GSSPs have been yet ratified. The base of the
Aptian as defined by Chron CM0R is within segment C1 or if
the stage is defined by the FO of Deshayesites oglanlensis the
base is in C2. If the base of the Upper Aptian Substage is defined by the FO of Epicheloniceras martini, the boundary is
within C7. In 2000 the base of the Albian was defined by the FO
of Leymeriella tardefurcata or Leymeriella schrammeni
schrammeni (Kennedy et al. 2000) dated at 112.46 Ma, which is
within C10. However new data from the pré-Guitard section in
southern France places the base Albian at the first appearance of
the planktic foraminifer Microhedbergella renilaevis Huber and
Leckie 2011 (Kennedy et al. 2014), which is in the middle of
Niveau Kilian. In CRETCSDB4 the FO of M. renilaevis is
113.29 Ma and Niveau Kilian is 113.36-113.24 Ma. The age of
carbon isotope stage 10 is 114.55-111.74 Ma.
The durations of the oceanic isotopic segments are measured by
the numerical age calibrations of the base of each carbon isotope event. The mean duration of 587 kyr is longer than the 400
kyr eccentricity cycle. The durations of the carbon isotope segments suggest that processes in addition to climate may have
been a driver of these segments. It should be noted that the longer segments could likely be subdivided by further refinement
of the carbon isotope curve with closer spaced samples. Increasing the number of segments could produce a cycle frequency
nearer 400 kyr.
ACKNOWLEDGMENTS
The excellent, thorough data collected and published by numerous authors provided the data for this stratigraphic experiment.
Research on the classic Mural Formation in Sonora by
Jayagopal Madhavaraju and Carlos González-León, Estación
Regional del Noroeste, Instituto de Geologica, Universidad
Nacional Autónoma de México, Hermosillo, prompted this
study. I appreciate the constructive reviews, which improved
the manuscript, and especially the support and suggestions of
Lucy Edwards.
REFERENCES
D’AREGENIO, B., FERRERI, V., WEISSERT, H., AMODIO, S.,
BUONOCUNTO, F. P. and WISSLER, L., 2004. Amultidisciplinary
approach to global correlation and geochronology. The Cretaceous
shallow-ater carbonates of southern Apennins, Italy. In: d’Argenio,
B., Fischer, A. G., Premoli Silva, I., Weissert, H. and Ferreri, V., Eds.,
Cyclostratigraphy: Approaches and case histories. SEPM Special
Publication No. 81: 103–122.
BERGGREN, W. A. and BURCKLE, L. H., Jr., 1997. The Pliocene-Pleistocene boundary in deep-sea sediments. In: Van
Couvering, J. A., Ed., The Pleistocene boundary & the beginning of
the Quaternary, 87–103. Cambridge University Press.
Stratigraphy, vol. 13, no. 1, 2016
BERNER, R. A. and KOTHAVALA, Z., 1999. GEOCARB III: A revised model of atmosphere CO2 over Phanerozoic time. American
Journal of Science, 301: 182–204.
BRALOWER, T. J., 1987. Valanginian-Aptian calcareous nannofossil
stratigraphy and correlation with the upper M-sequence magnetic
anomalies. Marine Micropaleontology 11: 293–310.
BRALOWER, T. J., COBABE, E., CLEMENT, B., SLITER, W. V.,
OSBURN, C. L. and LONGORIA, J., 1999. The record of global
change in mid-Cretaceous (Barremian-Albian) sections from the Sierra Madre, Northeastern Mexico. Journal of Foraminiferal Research, 29: 418–437.
BURLA, S., HEIMHOFER, U., HOCHULI, P. A., WEISSERT, H. and
SKELTON, P., 2008. Changes in sedimentary patterns of coastal and
deep-sea successions from the North Atlantic (Portugal) linked to
Early Cretaceous environmental change. Palaoegeography,
Palaeoclimatology, Palaeoecology, 257: 38–57.
CARNEY, J. L. and PIERCE, R. W., 1995. Graphic correlation & composite standard databases as tools for the exploration biostratigrapher. In: Mann K.O. and Lane H.R., Eds., Graphic Correlation,
23–43. SEPM (Society for Sedimentary Geology), Tulsa, Special
Publication 53.
CHANNELL, J. E. T., LOWRIE, W. and MEDIZZA, F., 1979. Middle
and Early Cretaceous magnetic stratigraphy from the Cismon section, Northern Italy. Earth and Planetary Science Letters, 42:
153–166.
CHANNELL, J. E. T., ERBA, E., MUTTONI, G. and TREMOLADA,
F., 2000. Early Cretaceous magnetic stratigraphy in the APTCORE
drill core and adjacent outcrop at Cismon (Southern Alps, Italy), and
correlation to the proposed Barremian-Aptian boundary stratotype.
Geological Society of America Bulletin, 112: 430–1443.
CHARTROUSSE, A. and MASSE, J.-P., 1998. Coalcomaninae
(Rudistes, Caprinidae) nouveaux de L’Aptien Inférieur des Mid Pacific Mountains. Geobios – Mémoire spécial no. 22:87–92.
CLARKE, L. J. and JENKYNS, H. C., 1999. New oxygen-isotope evidence for long-term Cretaceous climate change in the southern hemisphere. Geology, 27: 699–702
doi:10.1130/0091-7613(1999)027<0699:NOIEFL>2.3.CO;2.
DI LUCIA, M., TRECALLI, A., MUTTI, M. and PARENTE, M., 2012.
Bio-chemostratigraphy of the Barremian-Aptian shallow-water carbonates of the southern Apennines (Italy):pinpointing the OAE1a in
a Tethyan carbonate platform. Solid E arth , 3:1–28,
doi:10.5194/se-3-1-2012.
EDWARDS, L. E., 1989. Supplemented graphic correlation: A powerful
tool for paleontologists and nonpaleontologists. Palaios, 4:
127–143.
FRIEDRICH, O., NORRIS, R.D. and ERBACHER, J., 2012. Evolution of
middle to Late Cretaceous oceans — A 55m.y. record of Earth’s temperature and carbon cycle. Geology, 40: 107–110; doi:
10.1130/G32701.1.
FÖLLMI, K. B., GODET, A., BODIN, S. and LINDER, P. 2006. Interactions between environmental change and shallow water carbonate
buildup along the northern Tethyan margin and their impact on the
Early Cretaceous carbon isotope record. Paleoceanography, 21:
PA4211, doi:10.1029/2006PA001313.
GAMACORTA, G., JENKYNS, H. C., RUSSO, F., TISKOS, H., WILSON, P. A., FAUCHER, G. and ERBA, E., 2015. Carbon- and oxygen-isotope records of mid-Cretaceous Tethyan pelagic sequences
from the Umbria-March and Belluno Basins (Italy). Newsletters on
Stratigraphy, 48: 299–323.
GIORGIONI, M., WEISSERT, H., BERNASCONI, S. M., HOCHULI, P.
A., COCCIONI, R. and KELLER, C. E., 2012. Orbital control on carbon cycle and oceanography in the mid-Cretceous greenhouse.
Paleoceanography, 27: PA1204, doi:10.1029/2011PA002163 .
GRADSTEIN, F., OGG, J. and SMITH, A., 2004. A geologic time scale
2004: Cambridge University Press, 589 p.
GRADSTEIN, F. M. OGG, J. G., SCHMITZ, M. D. and OGG, G., 2014.
The Geologic Time Scale 2012. Elsevier, 2 vol., 1176 p.
HARLAND, W. B., ARMSTRONG, R. L., COX, A. V., CRAIG, L. E.,
SMITH, A. G. AND SMITH, D. G., 1990. A geologic time scale 1989:
Cambridge University Press, 263 p.
HAY, W. W., 2009. Cretaceous oceans and ocean modeling. In: Hu, X.,
Wang, C., Scott, R. W., Wagreich, M. and Jansa, L., Eds., Cretaceous
Oceanic Red Beds: Stratigraphy, Composition, Origins, and
Paleogeographic and Paleoclimatic significance. SEPM (Society for
Sedimentary Geology) Special Publication No. 91, 243–271.
HERRLE, J. O., KÖBLER, P., FRIEDRICH, O., ERLENKEUSER, H.
and HEMLEBEN, C., 2004. High-resolution carbon isotope records of
the Aptian to Lower Albian from SE France and the Mazagan Plateau
(DSDP Site 545): a stratigraphic tool for paleoceanographic and
paleobiologic reconstruction. Earth and Planetary Science Letters,
218: 149–161.
HU, X., SCOTT, R.W., CAI, Y., WANG, C. and MELINTEDOBRINESCU, M.C. 2012. Cretaceous oceanic red beds (CORBs):
Different time scales and models of origin. Earth-Science Reviews,
115:217–248.
HUANG, C., HINNOV, L., FISCHER, A. G., GRIPPO, A. and HERBERT, T., 2010. Astronomical tuning of the Aptian Stage from Italian
reference sections. Geology, 38:899-902; doi: 10.1130/G31177.1.
ERBA, E. and LARSON, R. L., 1998. The Cismon APTICORE (Southern Alps, Italy): A “reference section” for the Lower Cretaceous at
low latitudes. Rivista Italiana di Paleontogia e Stratigrafia, 104:
181–192.
HUCK, S., HEIMHOFER, U., IMMENHAUSER, A. and WEISSERT,
H., 2013. Carbon-isotope stratigraphy of Early Cretaceous (Urgonian)
shoal-water depsoits: Diachronous changes in carbonate-platform production in the north-western Tethys. Sedimentary Geology, 290:
157–174. Dx.doi.org/10.1016/j.sedgeo.2013.03.016.
ERBA, E., CHANNELL, J. E. T., CLAPS, M., JONES, C., LARSON,
R., OPDYKE, B., PREMOLI SILVA, I., RIVA, A., SALVINI, G. and
TORRICELLI, S., 1999. Southern Alps, Italy: A “reference section”
for the Barremian-Aptian interval at low latitudes. Journal of
foraminiferal Research, Washington D.C., vol. 29, p. 371–391.
HUCK, S., STEIN, M., IMMENHAUSER, A., SKELTON, P. W.,
CHRIST, N., FÖLLMI, K. and HEIMHOFER, U., 2014. Response of
proto-Atlantic carbonate-platform ecosystems to OAE 1a-related
stressors. Sedimentary Geology, 313: 15–31.
dx.doi.org/10.1016/j.sedgeo.2014.08.003.
ERBACHER, J., THUROW, J. and LITTKE, R., 1996. Evolution patterns of radiolaria and organic matter variations: A new approach to
identify sea-level changes in mid-Cretaceous pelagic environments.
Geology, 24: 499–502.
ICE, R. G. and MCNULTY, C. L., 1980. Foraminifers and calcispheres
from the Cuesta del Cura and lower Agua Nueva(?) formations (Cretaceous) in east-central Mexico. Transactions of the Gulf Coast Association of Geological Societies, 30: 403–425.
33
R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
JARVIS, I., GALE, A. S., JENKYNS, H. C. and PEARCE, M. A., 2006.
Secular variation in Late Cretaceous carbon isotopes: a new 13C carbonate reference curve for the Cenomanian-Campanian (99.6-70.6
Ma). Geological Magazine, 143: 561–608.
JENKYNS, H. C., 1995. 6. Carbon-isotope stratigraphy and
paleoceanographic significance of the Lower Cretaceous shallow-water carbonates of Resolution Guyot, Mid-Pacific Mountains.
In: Winterer E., Sager, W. W., Firth, J. V. and Sinton, J. M., Eds., Proceedings of the Ocean Drilling Program, Scientific Results, vol. 143:
99–104.
JENKYNS, H. C., 2010, Geochemistry of oceanic anoxic segments .
Geochemistry, Geophysics, Geosystems, 11, Q03004.
doi:10.1029/2009GC002788.
JENKYNS, H. C., GALE, A. S. and CORFIELD, R. M., 1994. Carbonand oxygen isotope stratigraphy of the English Chalk and Italian
Scaglia and its palaeoclimatic significance. Geological Magazine,
131: 1–34.
JENKYNS, H. C. and WILSON, P. A., 1999. Stratigraphy, paleoceanography, and evolution of Cretaceous Pacific guyots: Relics from a
Greenhouse Earth: American Journal of Science: 299:341–392.
KELLEY, S. P., 2003. 7 Volcanic inputs. In: Skelton, P.W., Ed., The Cretaceous World, 209–248. The Open University, Cambridge University Press.
KENNEDY, W. J., GALE, A. S., HUBER, B. T., PETRIZZO, M. R.,
BOWN, P., BARCHETTA, A. and JENKYNS, H. C., 2014. Candidate Global Boundary Stratotype section and point for the base of the
Albian Stage: The first appearance of the planktonic foraminiferan
Microhedbergella renilaevis Huber & Leckie, 2011 in the Marnes
Bleues of the Col De Près-Guittard Sectioin, Drôme, France. Cretaceous Research, 51: 248–259.
KUMP, L. R. and ARTHUR, M. A., 1999. Interpreting carbon-isotope
excursions: carbonates and organic matter. Chemical Geology
161:181–198.
LARSON, R. L. and ERBA, E., 1999. Onset of the mid-Cretaceous
greenhouse in the Barremian-Aptian: Igneous segments and the biological, sedimentary, and g eochemical responses.
Paleoceanography, 14: 663–678.
LECKIE, R. M., BRALOWER, T. J. and CASHMAN, R., 2002. Oceanic anoxic segments and plankton evolution: Biotic response to tectonic fording during the mid-Cretaceous. Paleoceanography, 17:
1–23. 10.1029/2001PA000623.
LONGORIA, J. F., 1974. Stratigraphic, morphologic and taxonomic
studies of Aptian planktonic foraminifera. Revista Espana
Micropaleontogia, Numero Extra, 1–107.
———, 1998. The Mesozoic of the Mexican Cordillera in Nuevo Leon,
NE Mexico. In: Longoria, J. F., Krutak, P. R. and Gamper, M. A.,
Eds., Geologic Studies in Nuevo Leon, Mexico. Sociedad Mexicana
de Paleontologia, Special Publication, p. 1–44.
MADHAVARAJU, J., SIAL, A. N., CARLOS GONZÁLEZ-LEÓN, C.
and NAGARAJAN, R., 2013. Carbon and oxygen isotopic variations in early Albian limestone facies the Mural formation,
Pitaycachi section, northeastern Sonora, Mexico. Revista Mexicana
de Ciencias Geológicas, 30: 526–539.
MENEGATTI, A. P., WEISSERT, H., BROWN, R. S., TYSON, R. V.,
FARIMOND, P., STRASSER, A. and CARON, M., 1998. High resolution 13C stratigraphy through the early Aptian “Livello Selli” of
the Alpine Tethys. Paleoceanography, 13: 530–545.
34
NUÑEZ-USECHE, F., MORENO-BEDMAR, J. A., COMPANY, M.
AND BARRAGÁN, R., 2014. A negative carbon isotope excursion
within the Dufrenoyia furcata Zone: proposal for a new episode for
chemostratigraphic correlation in the Aptian. Carnets de Géologie
[Notebooks on Geology], 14: 129–137.
OGG, J. G., HINNOV, L. A. and HUANG, C., 2012, Cretaceous. In:
Gradstein, F. M., Ogg, J. G., Schmitz, M. and Ogg, G., 2012, Eds., The
Geologic Time Geologic Time Scale 2012. Elsevier B.V., Amsterdam. DOI:10.1016/B978-0-444-59425-9.00027-5.
PETRIZZO, M. R., HUBER, B. T., GALE, A. S., BARCHETTA, A. and
JENKYNS, H. C., 2012. Abrupt planktic foraminiferal turnover
across the Niveau Kilian at Col de Pré-Guittard (Vocontian Basin,
southeast France): new criteria for defining the Aptian/Albian
boundary. Newsletters on Stratigraphy, 45: 55–74.
QUESNE, D. and FERRY, S., 1995. Detailed relationships between platform and pelagic carbonates (Barremian, SE France). In: House,
M.R. and Gale, A.S., Eds., Orbital forcing timescales and
cyclostratigraphy. Geological Society, Special Publication 85:
165–176.
REBOULET, S., RAWSON, P. F., MORENO-BEDMAR, J. A.,
AGUIRRE-URRETA, M. B., BARRAGÁN, R., BOGOMOLOV,
R., COMPANY, M., GONZÁLEZ-ARREOLA, C., STOYANO-VA,
V. I. , L U K E N E D E R , A . , MAT R IO N , B . , MIT TA , V. ,
RANDRIANALY, H., VASICEK, Z., BARABOSHKIN, E. J.,
BERT, D., BERSAC, S., BOGDANOVA, T. N., BULOT, L. G.,
LATIO, J.-L., MIKHAILOVA, I. A., ROPOLPO, P. and SZIVES, O.,
2010. Report on the 4th International Meeting of the IUGS Lower
Cretaceous Ammonite. Cretaceous Research, 30: 496–502.
ROBASZYNSKI, F., CARON, M., AMÉDRO, F., DUPUIS, C.,
HARDENBOL, J., GONZALEZ DONOSO, J. M., LINARES, D.
and GARTNER, S., 1993. Le Cénomanien de la région de Kalaat
Senan (Tunisie centrale): Litho-biostratigraphie et interprétation
séquentielle. Revue de Paléobiologie, 12: 351–505.
SALTZMAN, M. R. and THOMAS, E., 2014. Chapter 11 – Carbon isotope stratigraphy. In: Gradstein, F. M., Ogg, J. G., Schmitz, M. D. and
Ogg, G. M., Eds., The Geologic Time Scale 2012, Vol. 1, 207–232.
Amsterdam, Elsevier.
SANCHEZ-HERNANDEZ, Y. and MAURRASSE, F. J-M. R., 2014a.
Geochemical characterization and redox signals from the latest
Barremian to the earliest Aptian in a restricted marine basin: El Pui
section, Organyà Basin, south-central Pyrenees. Chemical Geology,
372: 12–31.
SANCHEZ-HERNANDEZ, Y. and MAURRASSE, F., 2014b. Chemostratigraphy of the Barremian-Aptian El Pui section, Organya Basin,
south central Pyrenees, Spain: Environmental conditions associated
with carbon isotope segments C2-C6, across OAE1a. Geological Society of America, Meeting Abstracts, Vancouver, British Colombia,
Paper 176–177.
SCOTT, R. W., 2014. Cretaceous chronostratigraphic database: construction and applications. Carnets de Geologie [Notebooks on Geology], 14: 1–13. http://paleopolis.rediris.es/cg/uk-index.html.
SCOTT, R. W., BENSON, D. G., MORIN, R. W., SHAFFER, B. L. and
OBOH-IKUENOBE, F. E., 2003. Integrated Albian-Lower
Cenomanian chronostratigraphy standard, Trinity River section
Texas. In: Scott, R. W., Ed., U.S. Gulf Coast Cretaceous Stratigraphy
and Paleoecology, 277–334. Perkins Memorial Volume: Gulf Coast
Section SEPM Foundation, Special Publications in Geology 1.
SCOTT, R. W., FROST, S. H. and SHAFFER, B. L., 1988. Early Cretaceous sea-level curves, Gulf Coast and southeastern Arabia. In:
Wilgus, C. K., Hastings, B. S., Kendall, C. G. St. C., Posamentier, H.
Stratigraphy, vol. 13, no. 1, 2016
W., Ross, C. A. and Van Wagoner, J. C., Eds., Sea-level changes: An
integrated approach, 275–284. Tulsa, Society of Economic Paleontologists and Mineralogists (SEPM). Special Publication 42.
SETON, M., GAINA, C., MÜLLER, R. D. AND HEINE, C., 2009.
Mid-Cretaceoous seafloor spreading pulse: Fact or Fiction? Geology, 37: 687–690.
SLITER, W. V., 1992. Cretaceous planktonic foraminiferal biostratigraphy and paleoceanographic segments in the Pacific Ocean with
emphasis on indurated sediment. In: Ishizaki, K. and Saito, T., Eds.,
Centenary of Japanese Micropaleontology, 281–299. Tokyo.
STRASSER, A., CARON, M. and GJERMENI, M., 2001. The Aptian,
Albian and Cenomanian of Roter Sattel, Romandes Prealpes, Switzerland; a high-resolution record of oceanographic changes. Cretaceous Research, 22: 173–199.
STEIN, M., FÖLLMI, K. B., WESTERMANN, S., GODET, A.,
ADATTE, T., MATERA, V., FLEITMANN, D., BERNER, Z., 2011.
Progressive palaeoenvironmental change during the Late
Barremian–Early Aptian as prelude to Oceanic Anoxic Event 1a: Evidence from the Gorgo a Cerbara section (Umbria-Marche basin,
central Italy). Palaeogeography, Palaeoclimatology, Palaeoecology, 302:396–406.
STEUBER, T., SCOTT, R. W., MITCHELL, S. F. and SKELTON, P. W.,
2015. Stratigraphy of Jurassic-Cretaceous genera of the Hippuritida
Newell (rudist bivalves). Carter, J., Ed., Treatise of Invertebrate Paleontology, in review.
VEIZER, J., ALA, D., AZMY, K., BRUCKSCHEN, P., BUHL, P.,
BRUHN, F., CARDEN, G. A. F., DIENER, A., EBNETH, S.,
GODDERIS, Y., JASPER, T., KORTE, C., PAWELLEK, F.,
PODLAHA, O. G. and STRAUSS, H., 1999. 87Sr/86Sr, 13C and 18O
evolution of Phanerozoic seawater. Chemical Geology, 161: 59–88.
WANG, P., TIAN, J. and LOURENS, L. J., 2010. Obscuring of long eccentricity cyclicity in Pleistocene oceanic carbon isotope records.
Earth Planetary Science Letters, 290: 319–330
doi:10.1016/j.epsl.2009.12.028
WEISSERT, H. and ERBA, E., 2004. Volcanism, CO2 and palaeoclimate:
a Late Jurassic-Early Cretaceous carbon and isotope record. Journal of
the Geological Society, London, 161: 695–702.
WEISSERT, H., JOACHIMSKI, M. and SARNTHEIN, M., 2008.
Chemostratigraphy. Newsletters on Stratigraphy, 42: 145–179.
WENDLER, I., 2013. A critical evaluation of carbon isotope stratigraphy
and biostratigraphic implications for Late Cretaceous global correlation. Earth-Science Reviews, Amsterdam, vol. 126, p. 116–146.
WENDLER, I., WENDLER, J., GRÄFE, K.-U., LEHMAN, J. and
WILLEMS, H., 2009. Turonian to Santonian carbon isotope data from
the Tethys Himalaya, southern Tibet. Cretaceous Research, 30:
961–979.
WISSLER, L., WEISSERT, H., MASSE, J.-P. and BULOT, L., 2002.
Chemostratigraphic correlation of Barremian and lower Aptian
ammonite zones and magnetic reversals. International Journal of
Earth Sciences (Geologische Rundschau), 91: 272–279.
WISSLER, L., FUNK, H. and WEISSERT, H., 2003. Response of Early
Cretaceous carbonate platforms to changes in atmospheric carbon dioxide levels: Palaoegeography, Palaeoclimatology, Palaeoecology,
200: 187–205. Doi:10.1016/S0031-0182(03)00450-4.
WISSLER, L, WEISSERT, H., BUONOCUNTO, F.P., FERRERI, V.
AND D’ARGENIO, B., 2004. Calibration of the Early Cretaceous
time scale: A combined chemostratigraphic and cyclostratigrahic approach to the Barremian-Aptian interval, Campania Apennines and
southern Alps (Italy). In: d’Argenio, B., Fischer, A. G., Premoli Silva,
I., Weissert, H. and Ferreri, V., Eds., Cyclostratigraphy: Approaches
and case histories. SEPM Special Publication No. 81: 123–133.
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R. W. Scott: Barremian-Aptian-Albian carbon isotope segments as chronostratigraphic signals: Numerical age calibration and durations
APPENDIX 1
Data Files of chemostratigraphic sections. ‘Morph’is a sorting code. Asterix denotes lines not used by GraphCor in the plotting or compositing steps.
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